JP5476315B2 - Optical assembly, array of optical devices, multi-energy imaging system and method - Google Patents

Description

  The present invention relates generally to optical technology, and more specifically to multilayer optical devices and methods of manufacturing multilayer optical devices.

  There are many methods that require a focused electromagnetic radiation beam. For example, energy dispersive X-ray diffraction (EDXRD) can be used to inspect checked baggage for the detection of explosive hazards or other contraband. Such an EDXRD system may have a high false positive rate because the X-ray signal after diffraction is weak. The weak X-ray signal can be attributed to various causes. First, the polychromatic X-ray spectrum used for EDXRD is inherently low in intensity because it is generated by the bremsstrahlung portion of the source spectrum. Second, because of X-ray source collimation, more than 99.99% of the source X-rays are eliminated and enter the baggage volume being analyzed. Third, some of the materials being sought, such as explosives, may be non-diffractive due to being amorphous. Fourth, the diffraction volume may be small. The last two restrictions are derived from the type of dangerous goods being searched for in the baggage, so all restrictions other than the second restriction are unavoidable. While the explosives detection situation is discussed, the above limitations apply equally to the medical environment.

  At low X-ray energies, such as 80 keV or less, a hollow glass polycapillary optical system is used as a low-power sealed tube (static anode) X-ray to increase the polychromatic X-ray flux density in the material being examined. Combined with the source. An example of a hollow glass polycapillary optical system is described, for example, in US Pat. No. 5,192,869. Glass is a low refractive index material, and air filling the hollow portion is a high refractive index material. These types of optics typically do not provide significant gain at energy levels above 80 keV. This is because as the energy level approaches and exceeds 80 keV, the difference between the refractive index of air and the refractive index of the glass becomes progressively smaller.

  Furthermore, such an optical system uses the concept of total reflection to reflect X-rays incident on the hollow glass capillary at an appropriate angle and return them to the hollow capillary, thereby allowing the X-ray source having a certain solid angle to pass through. A collimated or focused beam is obtained at the output of the optical system. As used herein, the term “collimate” refers to changing the divergence of an EM radiation beam from an essentially divergent electromagnetic (EM) beam. Typically, only about 5% of the solid angle of the EM source is captured by the input of such known optics.

  In addition, since known optical systems use air as one of the materials, such optical systems cannot be placed in a vacuum. For this reason, the possibilities of using known optical systems are limited.

  Shaping the X-ray spectrum to optimize for a specific application is a widely used procedure. Reducing spectral shape changes, such as either the low energy x-ray relative ratio or the high energy x-ray relative ratio, can provide optimal specimen imaging in some cases. One artifact commonly found in radiography and tomography imaging is that low energy x-rays in the typical bremsstrahlung (polychromatic) spectrum are preferentially attenuated as the beam enters and penetrates the material. Arise from the facts. This effect leads to an increase in the average energy of the beam as it enters and penetrates the specimen, biasing the relationship between the intensity of the transmitted beam and the amount of material that has been penetrated and transmitted. This bias appears as an artifact in any image reconstructed from attenuated data, such as artifacts caused by beam hardening in computed tomography. Some of these artifacts can be mitigated by using an X-ray beam with a small energy spread. Specifically, if the beam intensity is kept constant with respect to the intensity of the same range of the original spectrum or is enhanced by the use of an optical system, a limited application of energy can be used for a particular application. The desired degree of attenuation can be provided, and an image optimal for spatial resolution and contrast sensitivity can be formed. Shaping the spectrum from a pleochroic energy distribution to a more monochromatic distribution can allow such an improvement of the x-ray image set.

  Spectral imaging also includes single energy distribution and multiple energy distribution. Multi-energy x-ray imaging, also referred to as dual energy imaging or energy discrimination imaging, has been demonstrated to provide information on specific material compositions within a scanned object for security, industrial and medical applications. Such energy discrimination imaging can be performed in many ways, including the use of two or more different X-ray spectra, which is often the most realistic approach. The problem is that the nature of such an examination is sequential, for example, image data is first generated using one spectrum and then using another spectrum. In one approach, the object of interest is scanned twice. A first complete projection data set is generated in the first scan at one energy, and then a second complete projection data set is generated in the second scan at the second energy. In many applications where high throughput is critical, the material management technique of physically scanning the object twice is because the sample composition is dynamic and / or the sample placement may eliminate repetitive scanning. Unacceptable.

US Pat. No. 6,934,359

  Conventional multi-energy x-ray imaging applications use source filters and / or high voltage modulation to rapidly change spectral characteristics on a time scale comparable to sequential view sampling time in typical CT scans. Such a filter consists of successively inserting filters of appropriate composition one after the other to preferentially attenuate relatively low x-ray energy. Such methodologies are limited in the extent to which attenuation can produce clearly separated energy intervals and severely limit the sensitivity of this approach to analyzing different materials. In some cases, high voltage modulation that produces different spectral characteristics has also been implemented, but with limited success. Differences in registration in image reconstruction projection due to sample movement between data sets acquired at different energies, and a small amount of X-ray path traversing the object experienced by modulating the X-ray beam in sub-view units Any approach that mitigates misalignment is difficult.

  The invention includes embodiments that relate to an optical assembly that includes an optical device and a filtering mechanism. The optical device transmits a desired range of x-ray energy through at least one of total reflection, diffraction and refraction. The optical device includes at least three conformal solid phase layers, the interface between the solid phase layers is non-gap, and the at least three conformal solid phase layers are at least one X-ray layer. Includes a direction change area. The filter mechanism filters out some energy from the beam transmitted by the optical device. The filtering mechanism is at least one of a filtering device provided outside the optical device and a filtering device integrated with the optical device.

  The invention includes embodiments that relate to an array of optical devices that includes a first optical portion that transmits high or low X-ray energy and a second optical portion that transmits low X-ray energy. Yes.

  The present invention includes embodiments that relate to a method for forming a high energy spectral image by subtracting a low energy spectral image from a high energy and low energy spectral image. The method includes transmitting high and low x-ray energy through the optical device using at least one of total reflection, diffraction and refraction. The method also includes filtering some energy from the beam transmitted by the optical device to form a high energy spectral image using the filtering mechanism, the filtering mechanism being applied to the optical device. On the other hand, it is at least one of a filtering device provided outside and a filtering device integrated with the optical device.

  The present invention includes an electron generation source, a target that forms X-rays when struck by electrons from the electron generation source, a vacuum chamber containing the target, and a window through which the X-ray exits the vacuum chamber. Embodiments relating to multi-energy imaging systems are included. The system also includes at least one optical device configured to transmit a desired range of x-ray energy.

  The present invention includes embodiments that relate to a method of manufacturing a multiple energy imaging system that filters low energy X-rays from high energy X-rays in an imaging system. The method includes providing a target configured to form x-rays when struck by an electron beam and providing at least one optical device in optical communication with the target. . At least one optical device is configured to transmit high x-ray energy or to transmit low x-ray energy.

  These and other advantages and features will be more fully understood from the preferred embodiments of the invention as listed in connection with the accompanying drawings.

It is a schematic diagram which shows the phenomenon of total reflection. 1 is a top schematic view of an optical device constructed in accordance with one embodiment of the present invention. FIG. FIG. 3 is a cross-sectional view of the optical device of FIG. 2 taken along line III-III. FIG. 3 is an end view of the optical device of FIG. 2. FIG. 3 is a perspective view of the optical device of FIG. 2. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a perspective view of an optical device constructed in accordance with one embodiment of the present invention. FIG. 1 is a schematic diagram of a deposition assembly constructed in accordance with one embodiment of the present invention. FIG. 1 is a schematic diagram of a deposition assembly constructed in accordance with one embodiment of the present invention. FIG. FIG. 6 shows process steps for manufacturing an optical device according to an embodiment of the invention. It is a block diagram of the conventional computerized tomography system. It is sectional drawing of the X-ray tube head using the optical system by one Embodiment of this invention. 1 is a schematic diagram of a pair of optical devices used with a target of a dual energy scanning system according to an embodiment of the invention. FIG. It is a schematic diagram of the filter wheel used with the optical apparatus of FIG. 1 is a schematic view of a splicing optical device used with a target of a dual energy scanning system according to an embodiment of the present invention.

Each of the embodiments of the invention described herein primarily utilizes the phenomenon of total internal reflection. Referring now to FIG. 1, the total reflection occurs when the incident angle is smaller than the critical angle theta _c. The critical angle θ _c of total reflection depends in particular on the choice of material, the relative refractive index difference between the materials, the photon absorption properties of the material, and the energy of the incident photons. By suitable material selection of the multilayer optical system described herein, a critical angle theta _c air - that is increased several times than the glass critical angle, more photons to allow satisfy the condition of total reflection Can do. This allows for photon transmission through a multilayer optical system that is even greater than is possible with, for example, a polycapillary optical system.

  Referring to FIGS. 2-5, a multilayer optical system 10 including an input surface 12 and an output surface 14 is shown. “Multilayer” means a structure having a plurality of layers, each layer having a single composition. As more specifically shown in FIGS. 3 and 4, the multilayer optical system 10 includes a plurality of layers of materials, and each layer has a different refractive index. For example, there are layers 16, 20 and 24 surrounding the core 50. The layer 15 is formed of a low refractive index material, and is disposed outside the core 50 in the radial direction and is in contact with the core 50. The core 50 may be formed of a high refractive index material, such as beryllium, lithium hydride, magnesium, or any other suitable element or compound having high refractive index and high X-ray transmission properties as well. is there. The core 50 may range from a diameter smaller than 1 micrometer to a diameter larger than 1 centimeter. Layer 20 is disposed radially outside layer 16 and radially inside layer 24.

  In one embodiment, each layer constituting the multilayer optical system 10 may be formed of a plurality of materials having a changing refractive index. For example, the layers 15, 19, 23 and 27 can be formed of a material having a low refractive index and high X-ray absorption. For example, a suitable material can be selected from osmium, platinum, gold, or any other suitable element or compound that also has low refractive index and high X-ray absorption properties. Further, the core 50 and the layers 16, 20 and 24 may be formed of a material having a high refractive index and high X-ray transparency. For example, a suitable material can be selected from beryllium, lithium hydride, magnesium, or any other suitable element or compound that also has high refractive index and high X-ray transmission characteristics. The diameter of the core 50 considers the position of the focal point of the X-ray radiation source with respect to the input surface of the optical system and the critical angle required for total reflection between the high refractive index of the core 50 and the low refractive index of the layer 15. Is calculated by

  By using a low-refractive index material and a high-refractive index material alternately arranged with high X-ray absorption characteristics and low X-ray absorption characteristics in each successive layer, the multilayer optical system 10 can reduce the principle of total reflection of electromagnetic radiation. Can be used. Specifically, divergent electromagnetic radiation beams 38, 40 and 42 emanating from electromagnetic radiation source 34 enter input surface 12 and are redirected to quasi-parallel photon beam 44 by the principle of total internal reflection and exit output surface 14. .

A multilayer optical system, such as optical system 10 according to embodiments of the present invention, collects a large solid angle X-ray source 34 and redirects photons containing polychromatic energy into a quasi-parallel photon beam. be able to. “Quasi-parallel” means that a divergent photon beam such as X-ray is collected and focused into an electromagnetic radiation beam or X-ray beam and exits the output surface 14 at an angle less than the critical angle θ _c. To do. This divergence makes the original source X-ray beam larger than the output surface 14 of the optical system 10 and larger than the parallel beam of X-rays generated by this optical system. Alternatively, multilayer optics according to embodiments of the present invention can be configured to generate a slightly focused beam, a highly focused beam, a slightly divergent beam, or a highly divergent beam. . “Slightly focused” means that the beam size at the point of interest (ie, where the beam diameter is a problem) is approximately the same as the beam at the output surface 14 of the optical system 10. . “Largely focused” means that the beam size at the point of interest is smaller than the beam at the output surface 14 of the optical system 10. “Slightly divergent” means that the beam size is larger than the quasi-parallel beam but smaller than the original source beam. “Largely divergent” means that the beam is the same size or larger than the original source beam. “Original beam” refers to an X-ray beam emitted from a source housing that does not have an optical system in the beam.

  The angle acceptance range of the multilayer optical system 10 is determined by the composition of the materials constituting the multilayer optical system 10, the macroscopic geometric configuration of the multilayer optical system 10, the thickness of the multilayer optical system 10, and the number of individual layers. The angular acceptance range can span a solid angle photon source from about 0 steradians to about 2π steradians. For ease of understanding, only a few layers are shown for the multilayer optical system 10. However, any number of layers, including up to hundreds, thousands or even millions of layers, can be produced to utilize the total reflection to form the various types of photon beams listed above. Please appreciate that you can.

  Another feature of the multilayer optical system 10 is that the core 50 and the layers 16, 20, 24 can have photon or X-ray redirecting regions. For example, layer 16 has a photon direction changing region 17 emanating from the center of curvature, layer 20 has a photon direction changing region 21 emanating from a second center of curvature, and layer 24 is a photon emanating from another center of curvature. A direction change area 25 is provided. The photon redirection regions 17, 21, 25 allow the diverging electromagnetic radiation beams 38, 40, and 42 to be parallel or near parallel to the beam 36, or vice versa. Selected to allow divergence. The minimum photon redirection region is determined by the minimum thickness that still allows a smooth surface, and is at least two atomic layers, or about 10 angstroms. The photon direction changing regions 17, 21, 25 each include a direction changing arcuate portion. The redirecting arcuate portions are selected so that each has a constant curvature. The curvature of each redirection arcuate portion may be the same as or different from the curvature of the other redirection arcuate portion. If each of the direction change arcuate portions of a specific photon direction change region is a straight line, the radius of curvature is infinite.

  By curving the multilayers 16, 20, 24 on the input side of the optical system 10, the direction of photons or electromagnetic radiation 38, 40, 42 entering the input surface 12 is changed to a quasi-parallel pencil beam 44, thereby outputting The photon flux density at the surface 14 can be increased more than the photon flux density of a direct source beam (X-ray beam without optics) at the same distance from the source 34. Depending on the number of layers in the multilayer optical system, a photon density gain for 100 keV photons that is 5000 times greater than the output of a conventional pinhole collimator can be obtained at the output intensity of the electromagnetic radiation from the multilayer optical system. Alternatively, the output surface 14 may be formed closer to the input surface 12, i.e. it may be placed in front of the region where photons are redirected to parallel rays, and the input electromagnetic radiation beams 38, 40, 42. It will be appreciated that it is possible to leave some divergence as it exits the output surface 14. Furthermore, it should be appreciated that the core 50 and any number of layers may not have a curved arc instead of having a cylindrical cross-sectional profile.

  An important feature of this optical system 10 is that the solid angle of the source photons collected by these layers is reduced when the X-ray transmissive layers, such as layers 16, 20, 24, are made sufficiently thin and as thin as a few nanometers. It is small enough to accept almost all X-rays entering the layer, ie the X-ray trajectory satisfies the critical angle condition for total reflection. This is different from a known optical system in which the X-ray transmission region has a thickness of about several microns and a photon locus does not satisfy the critical angle condition of total reflection, so that a considerable number is absorbed by the reflection interface. In addition, the X-ray absorption layer is several orders of magnitude thinner than known optical systems, and the X-ray transmission of known optical systems is several orders of magnitude smaller than the optical systems described in this application. Furthermore, the total length of the optical system (from the input surface 12 to the output surface 14) is sufficiently short so that photon loss is minimized.

  Another feature of the multilayer optical system 10 is that individual layers can be conformally formed on top of each other through manufacturing techniques that will be described later. This conformal configuration of the layers allows the multilayer optical system 10 to be utilized in a vacuum environment. Prior art optical systems use air as the high refractive index material. Such an optical system cannot be used in a vacuum environment. In addition, the multilayer optical system 10 can be used for applications that operate at energy levels above 60 keV, such as X-ray diffraction, medical and industrial CT imaging, medical and industrial X-ray, and cargo inspection, to name a few. Can be used. Some of these applications can work with energy levels as high as 450 keV.

  Referring now to FIG. 6, a multi-layer optical system 110 is shown that includes a plurality of layers 113a-113n stacked on top of each other between the input surface 112 and the output surface 114. And has a polygonal outer shape. As shown, the intermediate layer of the multilayer optical system 110 is the layer 113mid. All of the layers other than the layer 113mid include a photon direction changing region disposed between the input surface 112 and the output surface 114. However, it should be appreciated that layer 113mid may include a photon direction change region, and other layers other than 113mid may lack a photon direction change region. In the illustrated design, diverging electromagnetic radiation is input to the input surface 112, redirected by the optical multilayer, and output from the output surface 114 to reduce the cone cone, such as a cone fan beam. It makes it possible to become a beam. Depending on where the output surface 114 is located relative to the photon redirection region, the fan beam may be parallel or near-parallel, and may be somewhat diverged but not to input electromagnetic radiation. On the other hand, it may still be focused. In addition, because the properties of the individual layers are conformal, the multilayer optical system 110 can be used in a vacuum environment.

  FIG. 7 shows a multilayer optical system 210 that includes an input surface 212 and an output surface 214. As in the case of the embodiment shown in FIG. 6, the multilayer optical system 210 includes individual layers with an intermediate layer interposed therebetween. The illustrated design enables a focused fan beam output. Similar to the embodiments described above, the multilayer optical system 210 can be used in a vacuum environment because the properties of the individual layers are conformal.

  FIG. 8 shows a multilayer optical system 310 having an input surface 312 and an output surface 314. Each layer is placed on a cone 150 that serves as a blank or mold for the individual layer. Through this design, the output beam exiting output surface 314 is shaped into a curved output, and this output is combined with a single curved diffractive crystal (not shown) to enable the generation of a cone beam of highly monochromatic radiation. be able to. Monochromatic radiation is used in several different applications such as X-ray diffraction. High monochromatic radiation is radiation in a very narrow energy range approximately equal to the energy range generated by diffracting from a single crystal. The curved diffractive crystal can be formed of any suitable material such as, for example, mica, silicon, germanium, or platinum, and the crystal is curved, for example, along the surface of a cone or cylinder. The suitability of any material used as a diffractive crystal depends on the material's diffraction intensity and lattice spacing. It should be appreciated that the multilayer optical system 310 is positioned between the source of electromagnetic radiation and the diffractive crystal to obtain the maximum photon flux density in the diffracted beam.

  5 to 7, when the filter is arranged on the input surface or output surface of the optical system, the output radiation of the optical system becomes quasi-monochromatic. Quasi-monochromatic radiation is radiation in a limited wavelength range that is wider than the high monochromatic range but narrower than the full bremsstrahlung spectrum from the x-ray source.

  9-12 illustrate various other possible embodiments of multilayer optics. 9 and 10 show a multilayer optical system having an output surface in the photon direction changing region, thereby enabling such an optical system to emit a highly divergent beam. 11 and 12 show a multilayer optical system in which an output surface is smaller than each input surface and emits a highly focused beam.

  Next, an apparatus used for forming a multilayer optical system will be described with reference to FIG. Specifically, a multi-layer optical deposition assembly 400 is shown as including a deposition chamber 402 and a movable shutter device 410. The deposition chamber 402 can be used for any suitable deposition technique including, for example, vapor deposition or thermal spray deposition. Suitable vapor deposition techniques include sputtering, ion implantation, ion plating, laser deposition, vapor deposition and jet vapor deposition. Vapor deposition techniques include heat, electron beam, or any other suitable technique that results in the deposition of significant material. Suitable thermal spray deposition includes combustion, arcing and plasma spraying. The deposition chamber 402 includes an input device 404 that directs deposition material into the deposition chamber 402. It should be appreciated that the input device 404 can include multiple inlet nozzles each associated with a particular deposition material. A blank 420 is disposed inside the deposition chamber 402. The blank 420 may be the core 50 or cone 150 described above with respect to the embodiments shown in FIGS. 4 and 8, or it may be a substrate that provides a support mechanism for the deposited layer. It should be appreciated that the blank 420 can take virtually any suitable geometric configuration consistent with the desired beam profile. Some examples of an almost infinite number of suitable geometric configurations include circular wafers, square pillars, cones, cylinders, and oval shapes.

  The shutter device 410 enables formation of a multilayer optical system in which each layer has a photon direction changing region. Specifically, when deposition material is input into the deposition chamber 402 through the input device 404, the shutter device 410 moves in the direction A relative to the blank 420. As the speed of the shutter device 410 decreases as the shutter device 410 moves in the direction A, the amount of deposited material in contact with the blank 420 gradually increases in the direction A, thereby causing the individual layers to have different thicknesses and photon direction changes. A multilayer optical system having a region can be formed. The movement and speed control of the shutter device 410 can be accomplished electronically by a digital control mechanism such as a microcontroller, microprocessor or computer. Alternatively, movement control may be accomplished manually, or may be accomplished mechanically, such as pneumatic or hydraulic.

  Individual layers can be deposited on the blank 420 by moving the shutter device 410 along direction A as each deposited material is input to the deposition chamber 402 through the input device 404, as shown in FIG. A multilayer optical system having conformal individual layers, such as a multilayer optical system, can be formed. When forming a multilayer optical system such as the multilayer optical system 110, the first layer to be deposited may be a layer adjacent to the intermediate layer 113mid. Subsequent layers leading to layer 113a can then be deposited including layer 113a. The partially formed multilayer optical system can then be turned over to deposit each layer up to the layer 113n, including the layer 113n. Further, if the deposition material is injected into the deposition chamber 402 at a constant rate, the shutter device 410 is programmed to start at the first rate and then return to the first rate after moving to the second different rate. In such a case, a multilayer optical system such as the multilayer optical system 210 shown in FIG. 7 can be formed. It should be appreciated that the deposition rate of the deposited material in the deposition chamber 402 may be varied as well.

  Instead of using the reciprocating device 410, it is also possible to move the input device 404 relative to the blank 420 at varying speeds. Furthermore, the blank 420 inside the deposition chamber 402 can be moved at a changing speed with respect to the input device 404.

  FIG. 14 illustrates a multilayer optical deposition assembly 500 that includes a deposition chamber 502 and a movable shutter 410. The deposition chamber 502 includes a device 404 that is a source of steam flow and a pair of rotating spindles 505. The spindle 505 can rotate in the direction B. Further, each of the spindles 505 includes a tip that contacts the blank 420 and holds the blank 420. By rotating the spindle 505 in the same direction B, the blank 420 can be rotated while introducing the deposition material into the deposition chamber 502 through the input device 404. By moving the shutter device 410 in the direction A and rotating the blank 420 in the direction B, a multilayer optical system such as the multilayer optical system 10 shown in FIG. 5 can be formed. Alternatively, the spindle 505 can remain non-rotated during the first set of deposition steps to form a layer adjacent to layer 113mid in FIG. 6 up to layer 113a. Next, the spindle 505 is rotated, the partially formed multilayer optical system is rotated 180 degrees, and a second set of deposition steps is performed to form each layer including the layer 113n including the layer 113n. The optical system 110 can be formed.

  Instead of using the shutter device 410, it is also possible to move the input device 404 at a changing speed with respect to the blank 420 while rotating the blank 420 by the spindle 505. Further, it is possible to move the spindle 505 and blank 420 inside the deposition chamber 402 at a varying speed relative to the input device 404.

  Alternatively, the input beam 404 may remain stationary while the blank 420 is rotated to focus the vapor beam along the blank 420 to different heights. The different deposition rates obtained form depth and laterally stepped inputs and outputs on the optical system, allowing the formation of a multilayer optical system such as the multilayer optical system 10 shown in FIG.

  FIG. 15 illustrates process steps for forming a multilayer optical system according to an embodiment of the invention. In step 600, a material having a predetermined refractive index with a predetermined photon transmission coefficient is deposited. The material is deposited on a blank or substrate which can be a core, cone or polygonal support mechanism. It should be appreciated that the blank or substrate may be incorporated within the multilayer optical system, such as the core 50, or simply a mold, such as the cone 150. Then, in step 605, another material having a predetermined refractive index with a constant photon transmission coefficient is deposited on the previous material in such a way as to conform and have minimal void space. It should be appreciated that each individual layer can be formed with a thickness in the range of 1 nanometer to thousands of nanometers. After step 605, step 600 and step 605 are repeated one after the other, e.g., multiple pairs of layers, each layer having a first refractive index with a first photon transmission coefficient and a second photon transmission. And a second layer having a second refractive index with a coefficient. The deposition of the first and second materials can be accomplished by any number of suitable processes such as, for example, vapor deposition, thermal spray deposition, or electroplating. As noted above, examples of suitable vapor deposition techniques include sputtering, ion implantation, ion plating, laser deposition (using a laser beam to vaporize the material (s) to be deposited), vapor deposition, Alternatively, jet vapor deposition (in which sound waves are used to vaporize the substance or substances to be deposited) can be used. Also, as described above, the vapor deposition technique may be heat, electron beam, or any other suitable technique that results in the deposition of significant material. Examples of suitable thermal spray deposition techniques include combustion, arcing and plasma spraying.

  It should be appreciated that the partially formed multilayer optical system may be rotated, vibrated, or moved during the deposition process. The partially formed multilayer optics can be rotated to provide a deposition process for depositing deposited material at different rates along the axis of the multilayer optics. In this way it is possible to collect a greater amount of electromagnetic radiation from the source at the input of the optical system, to output a parallel or near-parallel electromagnetic radiation beam from a multilayer optical system, or to multilayer Forming multi-layer optical systems with various configurations and profiles that allow the electromagnetic radiation beam output from the optical system to be shaped as a pencil beam, cone beam, fan beam or arcuate curve as an example Can do.

  The multilayer optical system according to each embodiment of the present invention can be used in various industrial applications. For example, multilayer optics configured to emit a quasi-parallel beam with a circular cross-section can be used for X-ray diffraction applications such as non-destructive inspection and X-ray backscatter applications. Multi-layer optics configured to emit a slightly focused beam with a circular cross-section can be used for X-ray diffraction applications, X-ray fluorescence applications, medical diagnostic or invasive therapeutic applications, and non-destructive inspection applications . Multi-layer optics configured to emit a large focused beam with a circular cross-section can be used in fluorescent X-ray applications such as medical diagnostic or invasive therapeutic applications such as microtumors, and non-destructive testing applications. Multilayer optics configured to emit a slightly divergent beam having a circular cross-section can be utilized in computed tomography and x-ray diagnostic system applications. Multi-layer optics configured to emit a large divergent beam with a circular cross-section is suitable for non-destructive inspection applications that require an enlarged field of view, as well as medical diagnostics or invasiveness that require an enlarged field of view such as imaging and treatment of large tumors Can be used for mold imaging and therapy.

  One example of the use of multilayer optics configured to emit a variety of beam shapes is in medical invasive treatments such as tumor treatment, where the shape of the optics is determined by the tumor shape. Such multilayer optics can focus X-rays on the tumor without exposing nearby healthy tissue and provide targeted therapy with minimal damage to surrounding healthy tissue it can.

  Multilayer formed to emit a fan beam in one plane that is quasi-parallel, slightly focused, highly focused, slightly diverged, or highly divergent in the plane of the plane The optical system can be used in computed tomography applications, X-ray diagnostic system applications, and non-destructive inspection applications. The fan beam may have a divergence that is the same as or greater than the source. Alternatively, a quasi-parallel fan beam in one plane that is quasi-parallel, slightly focused, highly focused, slightly diverged or highly divergent within this fan plane Multi-layer optics configured to emit light generates a beam having a rectangular cross-section that can be utilized in computed tomography applications, as well as non-destructive and medical inspection applications.

  Also, a multilayer optical system formed to emit a fan beam in one plane that diverges slightly or greatly in the transverse direction of the fan beam plane is provided for expanding the field of view. It can be used for medical invasive applications such as close-up imaging. The divergence in the transverse direction of the fan beam plane is equal to or greater than the source divergence. A fan beam in one plane, which is shaped to emit a fan beam that is quasi-parallel, slightly focused, highly focused, slightly focused, slightly diverged or highly divergent to the fan plane. The multilayer optical system can be used for computer tomography application, X-ray diagnostic system application and non-destructive inspection application. The fan beam may have a divergence that is the same as or greater than the divergence of the source.

  A multilayer optical system coupled to a diffractive crystal can generate a quasi-parallel monochromatic fan beam that can be used for medical imaging and invasive therapy if the intensity is sufficiently high. Such monochromatic imaging reduces patient-side x-ray dose while increasing resolution by, for example, suppressing cone beam artifacts and reducing fringes / shadows such as those that can accompany beam hardening effects.

  FIG. 16 shows a conventional acquisition system 700 used in an object detection system, such as a computed tomography (CT) scanner. Acquisition system 700 includes a scanner 702 formed from a support structure that includes one or more stationary or rotating distributed x-ray radiation sources (not shown in FIG. 16); One or more stationary or rotating digital detectors (not shown in FIG. 16) are contained internally. These will be described later. The scanner 702 is configured to accommodate a table 704 or other support for a scan object, such as baggage or bag, or a patient, for example. The table 704 can be moved through the scanner's bore to appropriately place the subject in the imaging volume or imaging plane scanned during the imaging sequence.

  The system further includes a radiation source controller 706, a table controller 708 and a data acquisition controller 710, all of which can operate under the direction of the system controller 712. The radiation source controller 706 adjusts the timing for the emission of x-ray radiation from a point around the scanner 702 towards the opposite detector element. This will be described later. The radiation source controller 706 can apply a trigger to one or more emitters of the distributed x-ray source at each time instant to create multiple projections or frames of measurement data. In some configurations, for example, the x-ray source controller 706 can sequentially apply a trigger for emission of radiation to collect adjacent or non-adjacent frames of measurement data around the scanner. Many such frames can be collected in a single test sequence, and a data acquisition controller 710 coupled to the detector elements as described below receives signals from the detector elements for storage and subsequent image reconstruction. For processing these signals. In configurations described below where one or more radiation sources rotate, the radiation source controller 706 can also command rotation of the gantry in which the distributed radiation source (s) are mounted. The operation of the gantry can also be controlled as a whole by the system controller 712 or a separate controller. The table controller 708 then in this situation appropriately places the table and subject in the plane from which the radiation is emitted, or generally in the interior of the volume being imaged. The table may be displaced between imaging sequences depending on the imaging protocol being used, or may be displaced between several imaging sequences. Also, in the configuration described below where one or more detectors or detector arcuate portions rotate, the data acquisition controller 710 also commands rotation of the gantry in which the detector (s) are mounted. Can do.

  System controller 712 generally coordinates the operation of radiation source controller 706, table controller 708, and data acquisition controller 710. In this way, the system controller 712 may cause the radiation source controller 706 to apply a trigger for the emission of X-ray radiation and coordinate such emission during the imaging sequence defined by the system controller. it can. The system controller can also coordinate table movement in coordination with emission such as collecting measurement data corresponding to a specific volume of interest, or in various imaging modes such as helical mode. . The system controller 712 also coordinates the rotation of the gantry in which the source (s), detector (s) or both are mounted. The system controller 712 also receives data acquired by the data acquisition controller 710 and coordinates data storage and processing.

  It should be noted that each controller and various circuitry described herein may be defined by hardware circuitry, firmware or software. Each controller may be separate hardware as shown in FIG. 16, or may be integrally configured as one piece of hardware. For example, the specific protocol of the imaging sequence is generally defined by code executed by the system controller. Also, the initial processing, adjustment, filtering, and other operations required for the measurement data acquired by the scanner can be performed on one or more of the components shown in FIG. For example, as described below, the detector element generates an analog signal representing the charge depletion of a photodiode located at each location corresponding to each pixel of the data acquisition detector. Such analog signals are converted into digital signals by electronic components inside the scanner and transmitted to the data acquisition controller 710. Partial processing may occur at this point, and each signal may eventually be sent to the system controller for further filtering and processing.

  The system controller 712 is also coupled to the operator interface 714 and one or more memory devices 716. The operator interface may be integrated with the system controller, generally for initializing the imaging sequence, controlling such sequence, and manipulating the measurement data acquired during the imaging sequence Includes an operator workstation. Memory device 716 may be located locally with respect to the imaging system or may be located partially or completely remote from the system. Thus, the imaging device 716 may include a local magnetic or optical memory, and may include a local or remote repository for measurement data for reconstruction. The memory device may also be configured to receive raw measurement data for reconfiguration, partially processed measurement data, or fully processed measurement data. A monitor (not shown) is also connected to the operator interface 714 and may allow observation of scan data, reconstruction data, or otherwise processed data.

  The system controller 712 or operator interface 714, or any remote system and workstation, may include software for image processing and reconstruction. As will be appreciated by those skilled in the art, such CT measurement data processing can be performed by a number of mathematical algorithms and techniques. For example, data acquired by the imaging system can be processed and reconstructed using conventional filtered backprojection techniques. Other techniques and techniques used with filtered back projection may be used. A remote interface 718 may be included in the system to transmit data from the imaging system to such a remote processing station or memory device.

  FIG. 17 illustrates a portion of an acquisition subsystem 800 that is used in an object detection system such as a computed tomography (CT) scanner such as the scanner 702 of FIG. Specifically, FIG. 17 shows an x-ray tube head 840. The multilayer optical system 10 is incorporated within the system 800. The alternating low and high refractive index materials with high and low X-ray absorption characteristics in each successive layer of the multilayer optical system 10 use the principle of total reflection of electromagnetic radiation. . Thus, the diverging X-ray beam emanating from the target 724 enters the input surface 12, is redirected and exits the output surface 14 as a photon beam 734. A multilayer optical system 10 that outputs any desired beam can be formed. The multilayer optical system 10 may be disposed outside or inside the window 748. In FIG. 17, the multilayer optical system 10 is shown in both positions for clarity.

  The multilayer optical system 10 can be formed by a method such as a photon beam 734 shown in FIG. 17 that generates an X-ray beam having a desired shape having an energy of 20 keV or more depending on the application. A multilayer optical system 10 that generates a limited x-ray cone beam as described above with respect to FIGS. 2-5 can be formed, but the output surface 14 is formed closer to the input surface 12, ie The exception is that the photon is placed in front of a region that is redirected to parallel rays. The input surface 12 may be flat or curved to accept most of the X-ray source cone from the target 724. Thereby, the input X-ray beam can be formed into a beam 734 having a desired shape.

  Although a third generation CT imaging system is described here in which the x-ray tube and detector rotate around the imaging volume, the optical system is an alternative configuration of third generation technology, such as an x-ray source and detection. The present invention is equally applicable to an industrial CT configuration in which the device is in a fixed state and the mounting table rotates the object at the time of data acquisition.

Referring to FIG. 18 in detail, a pair of optical devices 10 _a , 10 _b are shown. Each of these optical devices 10 _a, 10 _b is similar to the optical device 10 described with particular reference to Figures 2-5. Differences of the optical device 10 _a, 10 _b is that the one is formed so as to pass high X-ray energy, the other is formed so as to pass low X-ray energies. Shaping or filtering the source spectrum with the optical devices 10 _a , 10 _b gives the possibility of generating a spectral shape with a sharp high energy block at the sub-view speed, thereby increasing the material separation sensitivity, The alignment problem can be solved. The ability to generate a spectrum with a desired spectral shape on a fast time scale makes such an optical device particularly useful for multi-energy imaging.

Using K-edge filter may provide a sharp low energy cut off each of the optical systems 10 _a, 10 _b. One embodiment includes that the vapor phase deposition of a direct K-edge filter across the optical system 10 _a, 10 _b. Alternatively, K-edge filter may be formed as an optical system 10 _a, 10 _b of the output or input and the aligned separate foil (foil). Each optical system 10 _a , 10 _{b then} has its own distinct K edge filter that is either integrated into the optical system or separate from the optical system.

A laminated structure which may optical device as illustrated ₁₀ a, 10 _b are in optical communication with the target 724 of the X-ray tube head 840 of the acquisition subsystem 800 (Figure 17). Specifically, the X-ray 733 formed by causing the electron beam to collide with the focal spot 725 of the target 724 propagates from the focal spot 725 toward the input surface 12 of the optical device 10 _a , 10 _b . Alternatively, each of the focal spots 725 may be located within a separate individual target spot relative to a single continuous target spot 724 or on a separate non-continuous target. May be. X-ray 733 is then focused by optical devices 10 _a , 10 _b as described above and exits the output surface as redirected X-ray 734. This geometry can be repeated to form an array of such spot pairs, in which case an array of distributed x-ray source spots is used.

  Many options are possible to help separate high and low energy signals. One such configuration uses an optical device with a separate K-edge filter to generate two signals with different energy distributions. To do this, an image is taken with one optical device, and then the image is taken again using both this optical device and a K-edge filter to remove low energy photons. Subtracting these two appropriately normalized signals results in a signal that is mostly low energy, while the signal generated by the combination of the optical device and the K-edge filter has a relatively high energy photon. A signal having

  Alternatively, two optical devices may be used with at least one K-edge filter. The two optical devices are made of materials that cause X-ray redirection and transmission of two photon energy ranges that may or may not overlap. Taking an image with these two optical devices, repeating the K-edge filter that cuts off the energy from the optical device and the low energy transmitting optical device, and subtracting these two appropriately normalized images, An image derived from only low energy passed by an optical system that transmits low energy is produced. This low energy spectral image can be obtained by subtracting this appropriately normalized high energy spectral image from the image formed by photons from the combination of the two optical devices and the K-edge filter. To obtain a sharper low energy block in low energy images, a second K-edge filter that blocks the lowest energy photons from the optical system may be included.

  Another option that can provide greater energy separation between the signals is to couple the optical device to separate the targets at different acceleration potentials, and sequentially by the X-rays emitted by each acceleration potential / optical system combination. The target image is taken.

In order to obtain image sets generated by different energy distributions quickly and with the best possible statistical definition, the filter wheel 775 (FIG. 19) can be used to perform sequential filtering of the signal. For example, to generate a dual energy photon distribution, the filter wheel 775 includes a portion 780 that is opaque to all photons and a window 782 that is transparent to all x-rays. Can be. These windows 782 are shown only partially around the filter wheel 775 for clarity only. Alternatively, window 782 is covered with a suitable filtering material such as that required to block low energy x-rays from the high energy spectrum when two optical devices are used for imaging. Also good. By rotating the filter wheel 775, place the partial 780 between the optical device 10 _a and the detector, thereby blocking the all the X-rays are then transmitted by the optical system 10 _a reaches the detector can do. At the same time, it is possible to allow to place the window 782 between the other of the optical device 10 _b and the detector, all of the X-rays are then transmitted by the optical system 10 _b reaches the detector. Then, by rotating the filter wheel 775, as the window 782 is disposed between the detector 750 and the optical device 10 _a, and disposed between the portion 780 and the optical device 10 _b and the detector 750 , so that X-rays from only the optical device 10 _a is received by the detector.

The optical devices _10a , _10b are each made to filter out several x-ray energy levels. Specifically, each optical device _10a , _10b is made from a suitable optical material that selectively redirects several energy levels of x-rays in the optical system, primarily by total internal reflection. The refractive index of each material used to make the optical device determines the high energy cutoff and establishes the high energy side endpoint of the emitted spectrum.

As noted above, each optical device includes alternating high and low refractive index materials deposited in multiple layers, with individual layers in the nanometer thickness range. Each layer at the input surface 12 of the optical device 10 is curved to different degrees to capture a large source angle, such as 45 degrees or more, and directs the X-rays into a closely collimated fan-shaped beam. Can be changed. As noted above, the combination of some sort of low energy X-ray filter, such as a K-edge filter and the high energy filter of the optical device 10 _a, 10 _b, is possible to generate a different spectral shapes effectively it can. The low energy filter may take the form of a stand-alone foil and may be located at a conventional optical system rear emission position or between the source focal spot and the optical device. Alternatively, these low energy filters may be vapor deposited or chemically plated at either the input or output end of each optical system. Another possibility is to incorporate a filter internally in the optical device as a dopant in the high refractive index material. Yet another method of filtering low energy from optical transmission is to produce an optical system that has a selectively rough interface. Surface roughness scatters the lowest energy, but does not affect high energy reflections. In addition, the internal filtering method includes selecting a different material that determines the critical angle of total reflection in the optical device, which is the highest X-ray energy transmitted by the optical device. decide. The energy spectrum generated by these optical system-filter alternative configurations is shaped to be significantly different from the intrinsic bremsstrahlung emission of the source to provide a much sharper high and low energy cutoff. Can do.

Another configuration for creating two different energy distribution images is shown in FIG. 20, which consists of two halves 10 ', 10 "of two different optical systems joined together to form a single unit. it includes forming a optical device 10 _c. creation of a single optical device 10 _c of this type, in order to potentially reduce the distance between the center of gravity of the two target spots 725, smaller Eigen beam spot dimensions can be used, more efficiently using target emission, reducing target load and improving image alignment.Switching from one beam to another is a filter Can be done by a filter wheel such as wheel 775

The difference between the optical devices 10 ', 10 "is that one transmits high x-ray energy 734' and the other transmits low x-ray energy 734". Shaping or filtering the source spectrum with the optical devices 10 ', 10 "and appropriately incorporated low spectral filters of each optical spectrum speeds up spectral shapes with sharp high energy cuts and low energy cuts per subview. The ability to generate a spectrum with the desired spectral shape on a fast time scale can be multiplexed with such an optical device. and particularly useful in the energy captured in. acquisition subsystem 800 (FIG. 17), the optical device 10 _c is in optical communication with a target 724 of the X-ray tube head 840 basis. When specifically stated, the focal point of the target 724 spot X-rays 733 formed by making an electron beam collide with 725 are: Focal spot 725 two two-halves 10 of the optical device 10 _c from ', 10 "respectively input surface 12' and 12" are propagated towards the. Then, X-rays 733 of the two as described above two half Part 10 ', 10 "exits the output surface as high and low energy X-rays 734', 734" focused and redirected with respect to the two optical devices _10a , _10b (FIG. 18).

  Yet another configuration includes a spatial integration that brings the low energy optics region and the high energy optics region closer together. A single optical device can be manufactured to include a number of different sets of high and low refractive index materials to allow a single optical system to generate multiple energy distributions simultaneously. In addition, in an optical system that generates a dual energy beam, for example, the portion of the optical device used to generate the low energy beam has a corresponding low energy filter (e.g., incorporated internally as a dopant) K edge filter). The filter wheel should then simply include alternating regions of open windows and K-edge filters for optical layers that transmit high energy x-rays. As mentioned above, the K-edge filter of the filter wheel is first photographed side by side with the optical system, then the open window of the filter wheel is photographed side by side with the optical system to obtain sequential images, and then appropriately Creating a dual energy image with spatially matched spots having essentially equivalent spot shapes (averaged over the nanometer layer structure of the optical system) by subtracting the normalized images Can do.

  As mentioned above, a K-edge filter can be incorporated as a dopant. As an example of a method for performing such doping, let us consider that low-energy photons are blocked using a nickel K-edge, and that a high-refractive index layer is made of a single material, LiH. The LiH layer is then doped with Ni by simultaneously depositing lithium hydride and nickel, and can contain the minimum amount of nickel required to shut off the desired low energy over the entire length of the optical system. . The required nickel concentration can be calculated from the total length of the optical system, the thickness of the X-ray transmission layer, and the desired degree of low energy cutoff. In the case of an optical system of about millimeter length, the number of nickel atoms is likely to be three orders of magnitude smaller than the number of lithium hydride molecules.

In the dual energy system described with respect to FIGS. 18-20, the alignment problem of the image reconstruction projection is reduced. By configuring a pair of optical devices 10 _a , 10 _b with a fast acting shutter, such as a filter wheel 775, each optical device is exposed one after the other, thereby producing any spectrum at a given time. It is possible to control whether it is released. Such an arrangement can provide an alternating spectral shape on a time scale of less than milliseconds, thereby reducing the alignment difference between the projection sets for the two energies.

  In another configuration, two optical devices can be used, one being focused into one x-ray focal spot and shaping the x-ray spectrum in a desired manner, such as generating a low energy spectrum. The second optical system is focused on the second x-ray focal spot and shapes the x-ray spectrum to produce a high energy spectrum. Each optical device redirects its output to explore the same spatial volume. The range of X-ray energy incident on the optical device is changed rapidly by appropriate grating formation of any X-ray focal spot or by redirecting a single beam to multiple X-ray focal spot positions. be able to. For example, to probe a scan object with a low energy spectrum, the opposite X-ray focal spot is gridded. If the two X-ray focal spot positions use the same acceleration potential, the optical device can filter the spectrum as desired. Alternatively, each X-ray focal spot location can use different acceleration potentials and similar optical devices to produce spectral differences. In yet another embodiment, both the accelerating potential and the optical device characteristics can be varied to shape the spectral characteristics of the X-ray beam. In addition, a beam filter can be used with the optics to further shape the spectrum as desired. Any of these approaches presented here may include iterations to provide multiple energy capabilities for a distributed array of x-ray spots.

  Such multi-energy systems can be used for applications other than computed tomography. For example, such a system can be used for X-ray diffraction as well as standard X-ray projection imaging. By using quasi-monochromatic X-rays, the optical system can maintain the required energy intensity and keep the scanning speed high.

Although the invention has been described in detail in connection with only a limited number of embodiments, it will be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alternatives, substitutions or equivalents not described herein, but within the spirit and scope of the invention. For example, the embodiments of the invention described with particular reference to Figures 17 to 20 refer to optical devices _{10,10 a, 10 b, 10 c} , such description is intended only for clarity of description It should be appreciated that any of the multilayer optical devices described herein may be incorporated as appropriate. In addition, although the single energy and dual energy approaches are discussed above, the present invention also encompasses approaches with more than two energies. In addition, while various embodiments of the invention have been described, it should be understood that each aspect of the invention may include only some of the described embodiments. Accordingly, the invention is not limited by the foregoing description, but is only limited by the scope of the appended claims.

10 multilayer optic 10 ', 10 "optics of a two halves 10 _{a, 10} b, 10 _c optical device 12, 12', 12" input face 14 outputs surface 15,19,23,27 low refractive index and high X-ray Absorbing material layer 16, 20, 24 High refractive index material High X-ray transmitting material layer 17, 21, 25 Photon redirection region 34 Electromagnetic radiation source 36 Beam 38, 40, 42 Divergent electromagnetic radiation beam 44 Quasi-parallel photon beam 50-core 110 multilayer optical system 112 input surface 113a to 113n layer 113mid intermediate layer 114 output surface 150 cone 210, 310 multilayer optical system 212, 312 input surface 214, 314 output surface 400, 500 multilayer optical system deposition assembly 402, 502 deposition chamber 404 Input device 410 Movable shutter device 420 Blank 505 Spindle 700 Acquisition system 702 Scanner 704 Table 706 Radiation source controller 708 Table controller 710 Data acquisition controller 712 System controller 714 Operator interface 716 Memory device 718 Remote interface 724 Target 725 Focus spot 726
733 X-ray 734 Photon beam 734 'High X-ray energy 734 "Low X-ray energy 742
744
748 window 775 filter wheel 780 opaque part 782 transparent window 800 acquisition subsystem 840 x-ray tube head

Claims (10)

An optical device for transmitting X-ray energy in the desired range through total internal reflection, includes a conformal solid layer of at least three layers, the interface between the adjacent solid phase layer be no gap An optical assembly comprising an optical device, wherein the at least three conformal solid phase layers include at least one X-ray redirection region for total internal reflection . Some of the energy from the beam having transmitted through a filtering mechanism for filtering out by the optical device, fill are integrated into filter device and the optical device is provided external to said optical device and a filtering mechanism is at least one of a data device, assembly according to claim 1. The assembly of claim 2 , wherein the filter device comprises at least one rough interface surface or dopant . 4. An assembly according to claim 2 or 3 , wherein the filter device includes a filter wheel. 5. An assembly according to any of claims 2 to 4, wherein the filter device comprises a vapor deposited or chemically plated material on the input or output surface of the optical device. The filter device includes one selection from different materials that determine the critical angle of total internal reflection in the optical device, the critical angle determining the highest x-ray energy transmitted by the optical device. Item 6. The assembly according to any one of Items 2 to 5 . A first optical portion that transmits first X-ray energy through total internal reflection ;
A second optical portion that transmits a second X-ray energy that is lower than the first X-ray energy ;
Either or both of the first and second optical portions include at least three conformal solid phase layers, the interface between the solid phase layers is non-gap, and the at least three layers The conformal solid phase layer includes at least one X-ray direction changing region that performs total internal reflection, and at least two of the at least three layers have different refractive indexes .
An array of optical devices. The first and second optical portions include opposing halves forming a single optical device;
8. The first optical portion is formed of a material that transmits high X-ray energy, and the second optical portion is formed of a material that transmits low X-ray energy. array. A step to gather the first image in X-ray energy through the optical device using the total internal reflection,
Collecting a second image with lower X-ray energy transmitted by the optical device using a filtering mechanism, wherein the filtering mechanism is provided external to the optical device and at least one of a filtering device which is integrated with the optical device, and the step,
Subtracting the second image from the first image;
With a method. An electron source;
A target that forms X-rays that diverge when impacted by electrons from the electron source;
A vacuum chamber containing the target;
A window through which the X-ray exits the vacuum chamber;
Receiving said X-rays diverging, Ru and an optical assembly according to any of claims 1 to 5 is configured to transmit the X-ray energy in the desired range,
Multi-energy imaging system.

Images